Estrogen which is known to be a female sex hormone is produced in human mainly by ovary, and known types include 17β-estradiol, estrone, and estriol.
Estrogen is involved in various physiological functions including propagation of endometrium, regulation of sexual functions, regulation of bone metabolism, and regulation of lipid metabolism, and therefore, estrogen depletion caused by aging or weakening of ovarian function results in symptoms such as climacteric disturbance, hypogonadism, autonomic imbalance, lipidosis, vasomotor disturbance, and osteoporosis.
In the meanwhile, prevention or improvement of such symptoms by direct administration of estrogen or estrogenic substance would be inappropriate since they have EDC (endocrine disrupting chemical) action.